<u>Acceleration = (change in speed) / (time for the change)</u>
(Note: That's all the Physics there is to this problem. The rest is all arithmetic.) =======================================
change in speed = (40 - 20) miles/hour = -20 miles/hour time for the change = 10 minutes
Acceleration = (-20 miles/hour) / (10 minutes) =
<em>-2 miles/hour per minute</em> .
That's a perfectly good and technically correct expression for acceleration. But obviously the units might make some people dizzy. So let's try to clean it up a little.
Notice that 10 minutes is 1/6 of an hour. So we could write the acceleration as
First segment: The airplane is descending slowly, with time and distance at a 3:1 ratio. It is probably approaching the airport
Second segment: The airplane is maintaining its altitude. It is probably waiting for the other planes to clear away
Third segment:The airplane descending rapidly, with time and distance at a 1:2 ratio. It is probably landing
Sorry, my bad. To find acceleration, we use v2-v1 /t 40mph - 20mph / 10 min 20mph/10min We can convert this to 20/6 miles per 10 minutes, and cancel out the 10 min to 20/6 miles, which is 10/3 miles